Top 10 Video Game Sequels

Vince from Awesome Games writes: 'There are two different kinds of sequels: one is a soulless cash in on the original (too many examples to list here), the other is a honed masterpiece that the creators should have nailed in the first place. The Godfather Part II, The Empire Strikes Back and Star Trek II: The Wrath of Khan are all prime examples from classic film franchises, but how can one narrow down the the top 10 video game sequels?'
(Diablo 2, Half-Life 2, Halo 2, Mass Effect 2, PC, PS3, Red Dead Redemption, Retro, Super Mario Bros., Wii, Wii U, Xbox, Xbox 360)